Process for the production of highindene-content hydrocarbon oils



Patented Apr. 14, 1942 UNITED STATES 2,279,778 PATENT OFFICE PROCESS FOR THE PRODUCTION OF HIGH- INDENE-CONTEN'I HYDROCAEBON OILS Karl H. Engcl, West Englewood, N. 1., assignor, by mesne assignments, to Allied Chemical & Dye Corporation, a corporation of New York Application May 15, 1940, ScriaiNo. 335,329

9 Claims. (Cl. 202-42) This invention relates to the production and purification of indene-containing oils, and more particularly to the production of hydrocarbon oils of a high indene content from hydrocarbon oils of relatively low indene content.

Indene has heretofore been recovered from crude indene-containing hydrocarbon oils by treating them with substances such as sodium amide or potassium hydroxide whereby the alkali metal compound combines with the indene to produce a compound which separates from the hydrocarbon oils. The indene is then recovered from the compound thus formed by hydrolysis. Indene has also been recovered from indene-containing hydrocarbon oils by fractionating the oils to obtain a fraction having an indene content of about 80% and then cooling the fraction to temperatures of about --25 C.

to cause the indene to freeze and separate from.

substantially below the distillation temperatures of the phenol-indene azeotrope and of indene itself, 'separation of the indene and non-indene oils by distillation may be efliciently carried out.

Moreover, phenol tends to inhibit heat polymeri-.

zation of the indene during distillation of the phenol-indene-containing oil mixture. The phenol is also readily separable from the distillate by extraction.

Indene-containing oils, as is well known, may be obtained by fractional distillation of coal tar oils, drip oils, carburetted water-gas tar oils, oilgas tar oils, and light oils recovered in coal gas of high indene content from oils of relatively low indene content. Other objects of this invention will appear from the following detailed description.

This application is directed to a species of the generic invention disclosed and claimed in my copending application Serial No. 335,331. The

species involves the distillation of hydrocarbon removed have substantially lower distillation temperatures than the distillation temperatures of indene and of the indenephenol azeotrope, so that on fractional distillation the non-indene oils are distilled off as azeotropic mixtures with phenol, leaving a hydrocarbon oil of high indene content in the still.

Phenol, I have found, is a particularly efiec tive agent for use in separating indene by the process of this invention; Since the phenol-- non-indene azeotropes distill at temperatures and water-gas operations. In'accordance with this invention, the indene-containing hydrocarbon oils are mixed with phenol so as to form azeotropes with indene and the non-indene oils and the mixture is fractionally distilled to efiect the separation of the non-indene azeotropes from the indene. Distillation may be carried out under reduced pressures if desired, thus permitting greater heat economy without affecting the efliciency of the separation of indene and non-indene oils. It should be noted the ratio of hydrocarbon oil to phenol in the azeotrope may increase at reduced pressures. Since the azeotropes formed by phenol with the non-indene oils are of the minimum-boiling type, it has been found desirable before the addition of the phenol to subject the indene-containing hydrocarbon oils to be treated according to the invention to ordinary fractional distillation in order to remove non-indene oils of substantially diiferent boiling range from indene, particularly those of substantially higher boiling range than indene.

The removal of these oils reduces the amount.

of phenol required for the distillation, minimizes contamination of the high-indene-content product by azeotropes formed of phenol and higher boiling non-indene oils, and increases the yield of indene by reducing the volume of material which must be distilled, thus lessening the amount of indene carried into the distillate.

The amount of phenol added to the indenecontaining hydrocarbon oil should be regulated so that there will not bean undue amount remaining in the still residue when fractional distillation is discontinued. However, there should be enough phenol-present so that the azeotropic ratio of phenol to non-indene oils in the distillate will be maintained throughout the fractionation. The entire amount of phenol may be added to the indene-containing hydrocarbon oil before fractionation or the phenol may be added gradually in a continuous or intermittent fashion during the course of thefractionation.

At the beginning of the fractionation the distillate consists almost entirely of the azeotropic mixture of phenol and the non-indene oils, but.-

as fractionation proceeds and the temperature approaches the distillation temperature of the phenol-indene azeotrope, the indene content of separate phenol.

the distillate gradually increases. The course of fractionation may be followed by taking samples of the distillate and testing them for their indene content. The point at which fractionation is discontinued depends upon theindene content of the hydrocarbon oil being treated and also upon the desired indene content of the final product. Thus the lower the indene content of the hydrocarbon oil being treated and the high indene-content hydrocarbon oil. If desired;

fractionation may be continued until substantially the entire indene content of the charge has been distilled, thereby recovering from the last distillate cut a hydrocarbon oil containing.

about 98% indene. Fractionation of the mixture, however, is ordinarily discontinued when the indene content of the distillate shows the still residue contains about 89% to 92% indene (exclusive of phenol, if any), and the still residue is then distilled straight, i. e. without fractionation. obtaining thereby the desired highindene-content hydrocarbon oil.

The distillate recovered during the course of the fractionation contains substantially all the phenol and varying amounts of indene, in addition to the non-indene oils removed from the indene-containing hydrocarbon oil. The distillate maybe treated in any suitable manner to recover the phenol. Preferably the phenol is extracted from the distillate oil with aqueous alkali in the form of a phenolate, and then recovered from the phenolate solution by blowing with carbon dioxide. The recovered phenol may then be reused. The distillate oil fractions, which contain appreciable quantities of indene, may be refractionated, as described, phenol being added as necessary, to recover the indene contained therein; or the distillate oil may be treated in the ordinary manner with sulfuric acid to polymerize the indene and obtain hydrocarbon oils for solvent purposes and the like.

The accompanying drawing is a flow diagram illustrating a preferred method of carrying out the process of my invention.

Reference numeral l indicates an azeotropic fractional distillation operation in which a mixture ol' phenol and a close-cut indene fraction, e. g. a drip oil high-flash naphtha'fraction of boiling range 176183 0., enter the process as indicated at 2 and are subjected to azeotropic distillation. product consists primarily of an azeotrope of phenol'and non-indene components'of the .oil. This mixture is washed with an aqueous alkali solution as indicated at 3 to convert phenol to phenolate; the resulting phenolate solution is blown with carbon dioxide asindicated at .4 to

Phenol vapor present' in the spent carbondioxide withdrawn at 5 may here covered by condensation. ThelowindeneIoil.

.65 from the alkah wash operation as ndicatedat 6, V Thus} for every 100 parts of crude higbflaSh as above stated may mntam-a'ppteqame qua-mil: napntha containing 18% indene, approximately from which phenol h s been removed, withdrawn As above indicated the overhead ties of indene; this oil may,' therefore,'ibe retrac tionated, with the use of phenol-or other aaeo"- j tropic agent if desired, to 'recove iinden "c'onf tained therein.

The high indene oil withdra moved by washing with aqueous alkali solution '1 'as residue-from the azeotropic fractionation may con'tain traces of phenol; phenol present intliis- "oil -may- -b'e're-"' ":parts of an oil tained;

as above indicated. The high indene oil is then subjected to distillation as indicated at I to produce an indene distillate which may contain up to about 198% indene. The high boiling residue which contains some indene may be treated to in parts by volume. The indene percentages were calculated from the relation of the specific gravity of the oil to thatof a similar oil of known indene content. v

Example 1.--500 parts of drip oil high-flash naphtha of a boiling range from 176 to-183" C., a specific gravity at 22 C. of 0.957 and an indene content of 78% were mixed with 125 parts of phenol. in a 32-ball 7-f0ot colunm. Distillate cuts of parts each were tested to determine their specific gravity, the phenol was then removed by washing with alkali, the ratio of distillate oil to phenol calculated, and the specific gravity of the phenolfree distillate oil determined. From the specific gravity of the phenol-free oil, its indene content was calculated. The following table shows the results of these tests:

Parts Sp.of Ratio dis- 8 .ol indene of disdistillate distillate airtime distillate tillatc cut at220. oil/phenol oil at22 0. oil

(2'. Percent 305 173.8 (No determinations made oi these fractions 2% 3'5 because of small size of fractions) Fractionationwas'jdiscontinued after 325 parts of distillate had been recovered and the still resitherein, 27 0. parts of an oil of specificgravity of 0.983 at.22 .C. and an indene content of 94%.

44 parts .of an oil containing 55% indene and 54 containing 94% indene were ob- When the same oil'was fractionated in the same column at the same ratewithout the use of phenol',-it was impossible toobtaiu an oil of higher indene content than about 81%.

This mixture was then fractionated Example 2.-500 parts of a crude carbolic oil high-flash naphtha cut boiling from 176 to 184 0., having a specific gravity of 0.951 at 22 C. and an indene content of 68% were mixed with 125 parts of phenol, the mixture was fractionated as in Example 1, with the following results:

\ Parts of distillate Ratio disdistillate oil/phenol indene distillate all So. gr. oi distillate cut at 22 0.

Column temp.

Percent Fractionation was discontinued after400 parts of distillate had been recovered. The still residue was then distilled straight, yielding, after removal of the small amount of phenol' contained therein, 220 parts of an oil of specific gravity at 22 C, of 0.980, and having an indenecontent Eccmple ;3.-500 parts of crude carbolic oil high-fiash'naphtha, boiling from 1:11 to 183 0., having a specific gravity of 0.958 at 22 C. l and an indene contentof 74% were mixed with 150 parts of phenol and themixture was fractionated in a packed column at a pressure of about 280 mm. of mercury. Distillate cuts were tested by washing the cuts with alkali to remove the phenol, calculating the ratio of distillate oil to phenol, and then determining the specific gravity of the distillate 011. From the specific gravity of the phenol-free oil, its indene content was calculated. The following table shows the results of these tests:

. Ratio dis- Sp. gr. of Indcm' in Parts oidistillatc 1 33 1mm oil/ distillate oil distillate phenol at 22 0. oil

C. Percent Fractionation was discontinued after 255 parts of distillate had been recovered and the still residue was then distilled straight, yielding, after removal of the remaining phenol contained there in, 305 parts of an oil of specific gravity of 0.983 at 22 C., and an indene content of 92%. Thus .for every 100 parts of crude high-flash naphtha containing 74% indene, approximately 37 parts of an oil'containing 52% indene and about 61 parts of an oil containing 92% indene were obtained.

If it is'desired to obtain pure indene from the hydrocarbon oils of high indene content produced according to this invention, the oils may be cooled to between about -10 and about 20 C. and the solid indene thus formed separated from the oils.

From the. above description it will be evident this invention provides a simple and inexpensive method of obtaining hydrocarbon oils of high indene content from hydrocarbon oils of relatively low indene content.

Since certain changes may be made in carrying out the above process without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense. Thus, while the above description refers to the addition of phenol to hydrocarbon oils of relatively low indene content, it will be understood that the .invention comprehends the production of hydrocarbon oils of high indene content from hydrocarbon oils containing indene and phenol inherently present in amount suflicient tojorm with the constituents of the oil azeotropes of the minimum-boiling type.

I claim:

1. In a method of producing a hydrocarbon oil of high indene content from a hydrocarbon oil of relatively low indene content, the step which comprises distilling the hydrocarbon oil of relatively low indene content in the presence of an amount of phenol suflicient to forman azeotrope with non-indene components of the oil.

2. In a method of producing a hydrocarbon oil of'high indene content from a hydrocarbon oilof relatively low indene content having a boiling range in the neighborhood of indene boiling point, the steps of fractionally distilling thehydrocarbon oil of relatively lowindene content in the presence of an amount of phenol suflicient to form an azeotrope with non-indene components of the oil, and recovering the hydrocarbon oil of high indene content.

3. In a method of producing a hydrocarbon oil of high indene content from a hydrocarbon oil of relatively low indene content, the steps of adding an amount of phenol suflicient to form an azeotrope with non-indene components of the oil to the hydrocarbon oil of relatively low indene content vobtained by the fractional distillation of coal tar oils, dripoils, carburetted watergas tar oils, oil-gas-taroils, and 'light oils recovered in coal gas and water-gas operations, fractionally distilling the mixture, and recovering the hydrocarbon oil of high indene content from the still residue.

4. In a method of producing a hydrocarbon oil hydrocarbon oil of high indene content from the still residue.

5. In a method of producing a hydrocarbon oil of high indene content froma hydrocarbon oil of relatively low indene content, the steps of adding an amount of phenol suflicientvto form an azeotrope with non-indene components of the oil to crude carbolic oil high-flash naphtha,

fractionally distilling the mixture, and recovering the hydrocarbon oil of high indene content from the still residue.

of indene boiling point, which comprises adding an amount of phenol suflicient to form an azeotrope with non-indene components of the oil to the hydrocarbon oil of relatively low indene content, fractionally distilling the mixture, recovering the hydrocarbon, oil of high indene content from the still residue, cooling the recovered oil to between about -10 and about -20 C., and separating pure indene from the. cooled oil.

8. In a method of producing a hydrocarbon oil of high indene content, the steps which comprise fractionally distilling a crude selected from the group coal-tar oils, drip oils, carburetted watergas tar oils, oil-gas tar oils and light oils recovered in coal-gas and water-gas operations to produce a hydrocarbon mixture of relatively low indene content having a boiling range in the neighborhood of indene boiling point, adding to the resulting hydrocarbon mixture an amount of phenol sufllcient to form azeotropes with non-indene components of the oil, fractionally distilling the mixture, recovering phenol from the distillate, recovering the hydrocarbon oil of high indene content from the still residue, cooling the recovered oil to between about .10 and about -20 C., and separating solid indene from the crude oil.

9. In a method of producing a hydrocarbon oil of high indene content, the steps which comprise fractionally distilling a crude selected from the group coal-tar oils, drip oils, carburetted water-gas tar oils, oil-gas tar oils and light oils recovered in coal-gas and water-gas operations to produce a hydrocarbon mixture of, relatively low indene content having a boiling range in the neighborhood of indene boiling point, adding to the resulting mixture an amount of phenol suflicient to form azetropes with non-indene components of the oil, fractionally distilling the mixture at a pressure less than atmospheric, and recovering the hydrocarbon oil of high indene content from the still residue.

KARL H. ENGEL. 

